One good way to start is by rethinking your color scheme. If you have a country or Asian theme, you may not even have to repaint your walls. Vintage homes favor simple, natural colors that don't overpower the room. White, yellow, cream and beige all work very well for vintage decorating. If you have any loud colors, put them away or tone them down with more subtle pieces.
Patterns are also prevalent in vintage décor. Although solid colors have a peaceful look, patterns add a lot of character and lend some visual interest to the room. Avoid modern designs like abstracts and geometrics. Instead, go for softer, more natural prints like flowers, leaves, and soft curves. Pair them with a solid-colored piece such as a plain curtain so that the pattern really stands out.
You may also want to invest in an area rug. Carpeting wasn't very popular back in the day, as it was expensive and not very practical to maintain. With area rugs, you get the same comfort and luxurious feel, but at a much lower price. Rugs also come in more colors and patterns than carpeting, so it's easy to find one that matches your vintage décor.
Finally, accessorize with some vintage or vintage-style pieces. If you have a collection of antique coins or figurines, now's the time to show them off. Place them on a wooden shelf or on your coffee table. If you have limited room, get a wall shelf instead—it frees up some floor space and makes your display even more visible. They don't have to be elaborate or expensive—as long as they fit in and reflect your tastes, they'll look great in your vintage home.